The ‘Flynn effect’ reverses after decades of rising and falling IQ: are we dumber now?

A study conducted by U.S. researchers at Northwestern University has revealed that the IQa marker of intelligence that has been increasing by three to five points per decade since 1932, a phenomenon known as ”intelligence quotient”.Flynn effect’, has begun to decline.

As the study, conducted on data from nearly 400,000 adults between the years 2006 and 2018, concludes, the ‘Flynn effect’ is reversing in some markers. Specifically, there was a significant decline in three of the four cognitive areas assessed.

The scores obtained in skills of verbal reasoning (logic, vocabulary), reasoning matrix (visual problem solving, analogies) and series of letters and numbers (computational/mathematical) skills decreased during the study period. On the other hand, the results related to 3D rotation skills (reasoning spatial) generally increased from 2011 to 2018, according to the results of this research, published recently in the journal Intelligence.

Composite ability scores (single scores derived from multiple pieces of information) were also lower for the more recently obtained samples. Differences in scores were present regardless of age, educational level, or gender..

Despite the decline in scores, one of the study’s authors, Elizabeth Dworak, stated that she does not want people to read these findings and think that “Americans are becoming less intelligent.”

“It doesn’t mean their mental capacity is less or more; it’s just a difference in markers. that favor older or newer samples,” Dworak, who is also a professor of Medical Social Sciences at Northwestern University Feinberg School of Medicine, said in a press release issued by Northwestern University. “It could simply be that they are getting worse at performing tests or specifically worse at performing these types of tests,” she added.

This paper did not examine the reasons for the decline in IQ, but the researcher explained that there are several scientific theories that include causes such as the dietary impoverishmenta poorer general state of health or changes in education or the environment.

“There is some debate about the causes of this decline, but not all of the markers are going down; one of them is going up,” Dworak said. “If all the markers were going in the same direction, we could make a little narrative about it, but that’s not the case. We need to do more research to go deeper into it,” he said.

To conduct this research, the study of scientists relied on data from the Synthetic Aperture Personality Assessment (SAPA) Project, a free online survey-based personality test that provides examinees with feedback on 27 temperament traits (e.g., adaptability, impulsivity, anxiety, mood) and their ability scores.